• Title/Summary/Keyword: base temperature

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Strength Characteristics of Reduced Activation Ferritic Steel for Fusion Blanket by TIG Welding (핵융합로 블랭킷용 저방사화 철강재료 TIG 용접부의 강도특성)

  • ;;;A. Kohyama
    • Journal of Welding and Joining
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    • v.21 no.1
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    • pp.87-92
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    • 2003
  • JLF-1 steel (Fe-9Cr-2W-V-Ta), reduced activation ferritic steel, is one of the promising candidate materials for fusion reactor applications. Tensile properties of JLF-1 base metal and its TIG weldments has been investigated at the room temperature, $400^{\circ}C$ and $600^{\circ}C$. The tensile strength of base metal (JLF-1) showed the level between those of weld metal and the Heat Affected Zone (HAZ). When the test temperature was increased from room temperature to high temperature ($400^{\circ}C$ and $600^{\circ}C$), both strength and ductility decreased or base metal, weld metal and the HAZ. The longitudinal specimens of base metal represented similar strength and ductility at room temperature and high temperature, compared to those of transverse specimens. Little anisotropy for the rolling direction was observed in the base metal of JLF-1 steel.

High Fatigue Life and Tensile Strength Characteristics of Low Activation Ferritic Steel(JLE-1) by TIG Welding (TIG용접한 저방사화 페라이트강(JLF-1)의 고온강도 및 피로수명특성)

  • Yoon, H.K.;Lee, S.P.;Kim, S.W.;Park, W.J.;Kohyama, A.
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.181-186
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    • 2001
  • JLF-1 steel (Fe-9Cr-2W-V-Ta), low activation ferritic steel, is one of the promising candidate materials fer fusion reactor applications. High temperature fatigue life and tensile strength of JLF-1 steel and its TIG welded joints were investigated at the room temperature and $400^{\circ}C$. The strength of base metal (JLF-1) is in between those of weld metal and the HAZ. When the test temperature was increased from room temperature to $400^{\circ}C$, both strength and ductility decreased for base metal, weld metal and the HAZ. The longitudinal specimens of base metal showed similar strength and ductility compared with those of the transverse specimens at room temperature and $400^{\circ}C$. Little anisotropy was observed in the JLF-1 steel base metal in terms of rolling direction. Fatigue limit of weld metal which was obtained from cross-weld specimen is 495MPa. Thus, the weld metal showed the higher fatigue limit than those of base metal at both room temperature and $400^{\circ}C$. Little anisotropy of fatigue properties was observed for JLF-1 base metal in terms of rolling direction. When the test temperature was increased from room temperature to $400^{\circ}C$, the fatigue limit of both base metal and weld metal decreased substantially.

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Degradation Propeties of Alkali-Activated Alumino-Silicate Composite Body Exposed to High Temperature (알칼리 활성화 알루미노실리케이트계 경화체의 고온 열화 특성)

  • Kim, Won-Ki;Kim, Hong-Joo;Lee, Seung-Heun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.11a
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    • pp.627-630
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    • 2005
  • This paper examines degradation properties of alkali-activated alumino-silicate composite body by NAS solution exposed to high temperature. Activators include sodium hydroxides and sodium silicate solution. In the result of experiment, flexural and compressive strength of AAS base mortar exposed to high temperature ($400\~600^{\circ}C$) was higher than alumina cement base mortar. Particularly, In case of compressive strength, alumina cement base mortar was decreased by about $60\~70\%$. While, AAS base mortar exposed to high temperature ($400\~600^{\circ}C$) was higher than that curing by room temperature. The above results showed that AAS base inorganic binder has a good mechanical properties exposed to high temperature($400\~600$).

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Base heat flux calculation along variable pressure ratio and base temperature condition on launch vehicle (압력 조건과 기저 온도 조건에 따른 기저 열단전단률 계산)

  • Kim, J.G.;Lee, J.W.;Choi, J.K.;Kim, K.H.
    • 한국전산유체공학회:학술대회논문집
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    • 2011.05a
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    • pp.318-320
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    • 2011
  • Numerical study was conducted to simulate the heat transfer on the real launch vehicle base. Three different base temperatures were chosen, to simulate the heat accumulation on the base. Moreover, six different pressure ratio conditions were used to express the different air conditions. As a result, the table that can used to estimate the base heat fox along the base temperature and pressure condition was made.

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Numerical Prediction of the Base Heating due to Rocket Engine Clustering (로켓엔진 병렬화에 의한 저부가열의 수치적 예측)

  • Kim Seong Lyong;Kim Insun
    • Journal of computational fluids engineering
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    • v.9 no.3
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    • pp.18-25
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    • 2004
  • Multi plume effects on the base heating have been Investigated with a CFD program. As the flight altitude increases, the plume expansion angle increases regardless of the single or clustered engine. The plume interaction of the clustered engine makes a high temperature thermal shear in the center of four plumes. At low altitude, the high temperature shear flow stays in the center of plumes, but it increases up to engine base with the increasing altitude. At high altitude, the flow from plume to base and the flow from base into outer free stream are supersonic, which transfers the high heat in the center of plumes to the base region. The radiative heat of the clustered engine varies from 220 kW/m² to 469 kW/m² with increasing altitude while those of the single engine are 10 kW/m² and 43.7 kW/m². And the base temperature of the clustered engine varies from 985K to 1223K, and those of the single engine are 483K and 726K. This big radiative heat of clustered engine can be explained by the active high temperature base flow and strong plume interactions.

A Study on Hot Cracking in Ni-Base Superalloy Welds (I) - Effect of Fe Contents on Solidification Cracking Susceptibility in Weld Metal - (Ni기 초내열합금 용접부의 고온균열에 관한 연구(I) - 용접금속의 응고균열 감수성에 미치는 Fe의 영향 -)

  • ;;Kazutoshi Nishimoto
    • Journal of Welding and Joining
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    • v.19 no.6
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    • pp.614-621
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    • 2001
  • A study was carried out to determine the solidification cracking susceptibility of Ni-base superalloy as a function of Fe content in base metal. Three kinds of Ni-base superalloys with three different levels of Fe content were used. The solidification cracking susceptibility was evaluated by the Trans-Varestraint test at four different strain levels. Quantitative analysis of crack revealed that the solidification crack length and the temperature range in which hot cracking occurred in fusion zone (Brittle Temperature Range, BTR) decreased with a decrease in Fe content. Further, the thermo-calc data indicated that the solidification temperature range also decreased with decreasing Fe content. From these results, it was deduced that the improvement of the solidification cracking susceptibility with decreasing Fe content was attributed to the decrease of the solidification temperature range.

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Study of the Device Characteristics of The Base Resistance Controlled Thyristor With The Self-Align Corrugated P-base (자기정렬된 물결모양 P-베이스를 갖는 베이스 저항 제어 사이리스터의 소자특성에 관한 연구)

  • Lee, Yu-Sang;Byeon, Dae-Seok;Lee, Byeong-Hun;Kim, Du-Yeong;Han, Min-Gu;Choe, Yeon-Ik
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.3
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    • pp.167-172
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    • 1999
  • The device characteristics of the base resistance controlled thyristor with self-align corrugated p-base is demonstrated for the first time with varying the n+ cathode width and the temperature form room temperature to $125^{\circ}C$. The experimental results show that the snap-back in the CB-BRT is significantly suppressed irrespective of the various n+ cathode width and the temperature as compared with that of the conventional BRT. The maximum controllable current of the CB-BRT is uniformly higher when compared with that of the conventional BRT over the temperature range from room temperature to $125^{\circ}C$.

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Transient Liquid Phase Bonding of Directionally Solidified Ni Base Superalloy, GTD-111(I) - Bonding Phenomena and Mechanism - (일방향응고 Ni기초내열합금 GTD-111의 천이액상확산접합(I))

  • 강정윤;권민석;김인배;김대업;우인수
    • Journal of Welding and Joining
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    • v.21 no.2
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    • pp.82-88
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    • 2003
  • The bonding phenomenon and mechanism in the transient liquid phase bonding(TLP Bonding) of directionally solidified Ni base superalloy, GTD-111 was investigated. At the bonding temperature of 1403K, liquid insert metal was eliminated by isothermal solidification which was controlled by the diffusion of B and Si into the base metal and solids in the bonded interlayer grew epitaxially from mating base metal inward the insert metal. The number of grain boundaries formed at the bonded interlayer was corresponded with those of base metal. The liquation of grain boundary and dendrite boundary occurred at 1433K. At the bonding temperature of 1453K which is higher than liquation temperature of grain boundary, liquids of the Insert metal were connected with liquated grain boundaries and compositions in each region mixed mutually. In Joints held for various time at 1453t phases formed at liquated grain boundary far from the interface were similar to those of bonded interlayer. With prolonged holding time, liquid phases decreased gradually and liquids of continuous band shape divided many island shape. But liquid phases did not disappeared after holding for 7.2ks at 1453k. Isothermal solidification process at the bonding temperature which is higher than the liquation temperature of the grain boundary was controlled by diffusion of Ti to be result in liquation than B or Si. in insert metal. (Received January 15, 2003)

Numerical Analysis on Radiative Heating of a Plume Base in Liquid Rocket Engine (플룸에 의한 액체로켓 저부면 복사 가열 해석)

  • Sohn C. H.;Kim Y. M.
    • 한국전산유체공학회:학술대회논문집
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    • 1999.11a
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    • pp.65-70
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    • 1999
  • Radiative heating of a liquid rocket base plane due to plume emission is numerically investigated. Calculation of flow and temperature fields around rocket nozzle precedes and thereby realistic plume shape and temperature distribution inside the plume are obtained. Based on the calculated temperature field, radiative transfer equation is solved by discrete ordinate method. The averaged radiative heat flux reaching the base plane is about $5kW/m^2$ at the flight altitude of 10.9km. This value is small compared with radiative heat flux caused by constant-temperature (1500K) plume emission, but it is not negligibly small. At higher altitude (29.8km), view factor between the babe plane and the exhaust plume is increased due to the increased expansion angle of the plume. Nevertheless, the radiative heating disappears since the base plane is heated to high temperature (above 1000K) due to convective heat transfer.

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Fundamental Study on Ni-Base Self-Fluxing Alloy Coating by Thermal Spraying(I) - Effect of Splat Behavior of Sprayed Particles on Mechanical Properties of Coating Layer - (Ni-기 자융성합금의 코팅에 관한 기초적 연구(I) - 용사입자의 편평거동이 코팅층의 기계적 특성에 미치는 영향 -)

  • Kim, Y.S.;Kim, H.S.;Nam, K.W.
    • Journal of Power System Engineering
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    • v.1 no.1
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    • pp.70-79
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    • 1997
  • Ni-base self-fluxing alloy powder particles were flame sprayed onto the SS400 mild steel substrate surface. The effects of both substrate temperature and spraying distance on the splat behavior of sprayed particles were examined. The results obtained are summarized as follows: 1) In the splat behavior of Ni-base self-fulxing alloy particles sprayed onto the SS400 mild steel substrate, splashing was observed under the room temperature condition. On the contrary, it showed circular plate pattern in the substrate temperature range over 373K. 2) It was cleared that there was close relationship between mechanical properties of coating layer and splat behavior of sprayed particles. 3) From the experimental results, optimum spraying conditions showed excellent mechanical properties in the case of Ni-base self fluxing alloy sprayed onto the SS400 mild substrate were 473K of substrate temperature and 250mm of spraying distance.

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